Fabricating hybrid plastic-glass lens

ABSTRACT

Fabricating a prescription optical element include providing a glass substrate layer and coupling an optical plastic layer to the glass substrate layer. A prescription surfaces is formed on an eyeward side of the optical plastic layer that is opposite an object side of the optical plastic layer. The object side is a planar surface that overlays the glass substrate layer and the glass substrate layer has a glass thickness to provide rigidity to the prescription optical element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of pending U.S. Non-Provisionalapplication Ser. No. 16/940,120, filed Jul. 27, 2020, which claims thebenefit of U.S. Provisional Application No. 63/003,643 filed Apr. 1,2020. U.S. Non-Provisional application Ser. No. 16/940,120, and U.S.Provisional Application No. 63/003,643 are expressly incorporated hereinby reference in their entirety.

BACKGROUND INFORMATION

Prescription lenses were traditionally fabricated out of glass beforetransitioning to predominantly plastic lenses. The conventionalmanufacturing technique for prescription lenses is to form aprescription surface specific to an individual from a plastic blank thathas a base curve. This technique works well for fabricating traditionaleye glasses, although the thickness and weight of traditionalprescription lenses constrain design, in some contexts.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 illustrates an example head-mounted device having a prescriptionoptical element, in accordance with aspects of the present disclosure.

FIG. 2A illustrates a hybrid plastic-glass lens blank that includes anoptical plastic substrate coupled to a glass substrate layer, inaccordance with an embodiment of the disclosure.

FIG. 2B illustrates forming a prescription surface in a hybridplastic-glass lens blank to form a prescription lens, in accordance withaspects of the disclosure.

FIG. 3 illustrates a hybrid plastic-glass lens blank that includes anoptical plastic layer, a glass substrate layer, and an intermediatelayer, in accordance with aspects of the disclosure.

FIG. 4 illustrates an example roll-to-roll bonding of an optical plasticlayer to a glass substrate layer, in accordance with aspects of thedisclosure.

FIG. 5 illustrates an example lamination technique of coupling anoptical plastic layer to a glass substrate layer, in accordance withaspects of the disclosure.

FIG. 6 illustrates a chuck securing a hybrid plastic-glass lens blankfor diamond-turning a prescription surface into the optical plasticlayer with a diamond bit in a subtractive process, in accordance withaspects of the disclosure.

FIG. 7 illustrates a plastic center thickness dimension of an opticalplastic layer at a central optical axis of a prescription surface, inaccordance with aspects of the disclosure.

FIG. 8 illustrates an example hybrid glass-plastic prescription opticalelement, in accordance with aspects of the disclosure.

FIG. 9 illustrates a flow chart for an example process of fabricating aprescription optical element, in accordance with aspects of thedisclosure.

DETAILED DESCRIPTION

Embodiments of a hybrid plastic-glass lens are described herein. In thefollowing description, numerous specific details are set forth toprovide a thorough understanding of the embodiments. One skilled in therelevant art will recognize, however, that the techniques describedherein can be practiced without one or more of the specific details, orwith other methods, components, materials, etc. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring certain aspects.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Throughout this specification, several terms of art are used. Theseterms are to take on their ordinary meaning in the art from which theycome, unless specifically defined herein or the context of their usewould clearly suggest otherwise.

Aspects of this disclosure are directed to lenses and prescriptionlenses. The disclosed prescription lenses may be incorporated into ahead-mounted device (e.g., augmented-reality glasses, virtual realityheadset, electronic glasses, or non-electronic eye glasses). In someaspects, the lenses for an AR system may have the following constraints:(1) one surface that is plano for mating with additional opticalelements of the optical assembly (e.g., an eye-tracking optical stack)and the other surface should be curved (e.g., concave) for providing theoptical power; (2) a size and weight requirement that are more stringentas compared to typical eyewear (e.g., center thickness being less than0.5 mm and total weight being less than 1 g); (3) little to no lensdeformation; and (4) compliance with national or international safetystandards. Existing lens blanks are typically made from plastic puckswhich are diamond-turned in a lab to a user's specifications. A plasticpuck (or blank) with a suitable base curve is selected and then aprescription surface is generated opposite the base curve so that thebase curve and the prescription surface combine to provide theprescription optical power specific to the individual. The thinnestprescription lenses that can be made with this approach are limited bythe low rigidity of purely plastic substrates. Accordingly, aspects ofthis disclosure include forming a plastic-glass hybrid lens blank whichcan be turned using existing tools.

Thus, a plastic substrate may be formed over a glass substrate to formthe hybrid plastic-glass hybrid lens blank. The plastic substrate may becast, molded, laminated, or bonded to the glass substrate. To preventseparation of the two layers, some aspects may include a coefficient ofthermal expansion (CTE) layer between the glass and plastic due to thematerial's differing thermal expansions. The glass base providesrigidity and mechanical support, while the plastic substrate allows forflexible surface shapes that may be formed through diamond turning. Insome aspects, the hybrid plastic-glass lens blank are fabricated to havea 500 um or less center thickness.

FIG. 1 illustrates an example head-mounted device 100, in accordancewith aspects of the present disclosure. The illustrated example ofhead-mounted device 100 is shown as including a frame 102, temple arms104A and 104B, and near-eye optical elements 110A and 110B. Optionaleye-tracking cameras 108A and 108B are shown as coupled to temple arms104A and 104B, respectively. FIG. 1 also illustrates an exploded view ofan example of near-eye optical element 110A. Near-eye optical element110A is shown as including a prescription (Rx) lens 120A, and at leastone additional optical element 130A. In some aspects, optical element130A may include one or more components for eye-tracking purposes, suchas in-field light sources, an optical combiner, etc. In an embodiment,optical element 130A includes a plastic layer configured to illuminatean eyebox area with near-infrared light. The plastic layer of opticalelement 130A may be configured to direct reflected near-infrared lightto camera 108A where the reflected near-infrared light is reflected froman eyebox area (e.g. a user's eye, brow, and/or cheek). The opticalelement 130A may also include a display layer such as a waveguide thatis configured to direct virtual images to an eye of a user ofhead-mounted device 100. There may be an airgap between lens 120A andoptical element 130A. Lens 120A may be bonded to optical element 130A,in other embodiments.

A head-mounted device, such as head-mounted device 100 is one type ofhead mounted device, typically worn on the head of a user to provideartificial reality content to a user. Artificial reality is a form ofreality that has been adjusted in some manner before presentation to theuser, which may include, e.g., virtual reality (VR), augmented reality(AR), mixed reality (MR), hybrid reality, or some combination and/orderivative thereof.

As shown in FIG. 1 , frame 102 is coupled to temple arms 104A and 104Bfor securing the head-mounted device 100 to the head of a user. Examplehead-mounted device 100 may also include supporting hardwareincorporated into the frame 102 and/or temple arms 104A and 104B. Thehardware of head-mounted device 100 may include any of processing logic,wired and/or wireless data interfaces for sending and receiving data,graphic processors, and one or more memories for storing data andcomputer-executable instructions. In one example, head-mounted device100 may be configured to receive wired power and/or may be configured tobe powered by one or more batteries. In addition, head-mounted device100 may be configured to receive wired and/or wireless data includingvideo data.

FIG. 1 illustrates near-eye optical elements 110A and 110B that areconfigured to be mounted to the frame 102. In some examples, near-eyeoptical elements 110A and 110B may appear transparent to the user tofacilitate augmented reality or mixed reality such that the user canview visible scene light 191 from the environment while also receivingdisplay light directed to their eye(s) by way of a display layer. Infurther examples, some or all of the near-eye optical elements 110A and110B may be incorporated into a virtual reality headset where thetransparent nature of the near-eye optical elements 110A and 110B allowsthe user to view an electronic display (e.g., a liquid crystal display(LCD), an organic light emitting diode (OLED) display, a micro-LEDdisplay, etc.) incorporated in the virtual reality headset.

The Rx lens 120A is shown as being disposed between the optical element130A and the eyeward side 109 of the near-eye optical element 110A. TheRx lens 120A may be fabricated in accordance with the embodiments ofFIGS. 2A-9 .

FIG. 2A illustrates a hybrid plastic-glass lens blank 210 that includesan optical plastic layer 270 coupled to a glass substrate layer 250, inaccordance with an embodiment of the disclosure. Conventional plasticlens blanks are 3-5 mm thick, whereas the hybrid plastic-glass lensblank 210 may be significantly thinner at dimension 213. A plastic lensblank that was less than 500 microns thick, for example, would notprovide the required rigidity for a prescription lens. Hybridplastic-glass lens blank 210 may have a dimension 213 that is 500microns or less while providing suitable mechanical rigidity. In FIG.2A, glass substrate layer 250 provides the rigidity for a prescriptionlens fabricated from a hybrid plastic-glass lens blank 210. Glasssubstrate layer 250 coupled to optical plastic layer 270 is rigid androbust enough to survive current environmental and safety tests. In anembodiment, glass substrate layer 250 (when coupled with optical plasticlayer 270) is thick enough to withstand 70 Newtons of force. In FIG. 2A,glass substrate layer 250 has a planar surface 253 disposed opposite ofanother planar surface 255. Glass substrate layer 250 may be less than400 thick, in some embodiments. Glass substrate layer 250 may be between200 and 300 microns thick, in some embodiments. Glass substrate layer250 may be less than 200 microns thick, in some embodiments. In FIG. 2A,glass substrate layer 250 has a planar surface 253.

Optical plastic layer 270 may include acrylate, polyurethane,polycarbonate, or other type of optical plastic layer 270 suitable forprescription lenses. Optical plastic layer 270 has a planar surface 275that is coupled to a planar surface 255 of glass substrate layer 250, inFIG. 2A. Optical plastic layer 270 may have a first refractive indexthat is substantially the same as a second refractive index of glasssubstrate layer 250.

FIG. 2B illustrates forming a prescription surface 277 in hybridplastic-glass lens blank 210 to form a prescription lens 211, inaccordance with aspects of the disclosure. FIG. 2B illustrates chuck 287securing hybrid plastic-glass lens blank 210 for diamond-turning aprescription surface 277 into the optical plastic layer 270 with adiamond bit 280 in a subtractive process. FIG. 2B illustrates a plasticcenter thickness dimension 279 of optical plastic layer 270 at a centraloptical axis 295 of the prescription surface 277. Prescription surface277 is formed opposite planar surface 275 of optical plastic layer 270.In an embodiment, plastic center thickness dimension 279 is less than200 microns. Dimension 279 may be less than 100 microns, in someembodiments. In an embodiment, dimension 279 is 50 microns or less.Glass substrate layer 250 may have a thickness 259 of 200 microns orless. A total center thickness of prescription lens 211 (e.g. dimension279 plus dimension 259) may be less than 500 microns. In a conventionalplastic lens, a center thickness that is 500 microns or less would notprovide suitable rigidity for the prescription lens. However, the hybridplastic-glass prescription lens 211 has the benefit of the rigiditycharacteristic of glass substrate layer 250. This allows prescriptionlens 211 to be significantly thinner and lighter than conventionallenses. Furthermore, plastic center thickness dimension 279 being 200microns or less allows for thermal expansion of optical plastic layer270 that is significantly greater than conventional plastic eye glasslenses. Prescription lens 211 may be used as lens 120 in FIG. 1 , forexample.

Previous designers have not been motivated to fabricate a hybridplastic-glass prescription lens because the plastic lenses are lightenough for conventional prescription lenses and have become incrediblyinexpensive to fabricate. In contrast, the disclosed hybridplastic-glass lens blanks and prescription lenses may be more costly andmore complicated to fabricate due to using a plurality of materials andadditional manufacturing process steps. Furthermore, the larger size ofthe conventional all-plastic prescription lens provides largermechanical features (e.g. bevel or groove on outside of prescriptionlens) that may make the prescription lens easier to secure toconventional eye-glasses frames. Yet, in some contexts, reducedthickness and weight of a prescription lens may be particularlybeneficial.

FIG. 3 illustrates a hybrid plastic-glass lens blank 310 that includesoptical plastic layer 270, glass substrate layer 250, and anintermediate layer 260, in accordance with an embodiment of thedisclosure. Intermediate layer 260 is disposed between optical plasticlayer 270 and glass substrate layer 250. Intermediate layer 260 may bean optically clear adhesive (OCA). Intermediate layer 260 may be indexedmatched to a refractive index of optical plastic layer 270 and/or glasssubstrate layer 250. Intermediate layer 260 may adhere glass substratelayer 250 to optical plastic layer 270. Even with intermediate layer 260added, hybrid plastic-glass lens blank 310 may have a dimension 313 thatis less than 1 mm. Hybrid plastic-glass lens blank 310 may have adimension 313 that is less than 500 microns.

In an embodiment, intermediate layer 260 has a coefficient of thermalexpansion (CTE) configured to provide axial flexibility and lateralflexibility of a prescription lens over temperature ranges that will beencountered by the prescription lens. Thus, intermediate layer 260 maybe configured as a CTE absorber layer.

Intermediate layer 260 may also be configured as a cushioning layer toabsorb at least a portion of mechanical shock that would be transferredbetween optical plastic layer 270 and glass substrate layer 250.Intermediate layer 260 may be considered a gel or semi-pliable layerthat is soft enough to deform without cracking under mechanical and/orthermal stress. A primer may be used as intermediate layer 260.Intermediate layer 260 may be an adhesion promoter that facilitatesbetter adhesion between optical plastic layer 270 and glass substratelayer 250. Intermediate layer 260 may include adhesives that arecommonly used to bond a display (e.g. LCD or OLED) with a displaycoverglass, for example.

FIG. 4 illustrates an example roll-to-roll bonding of optical plasticlayer 270 to glass substrate layer 250, in accordance with aspects ofthe disclosure. Roll-to-roll bonding is one example of fabricating ahybrid plastic-glass blank of the disclosure. In FIG. 4 , rolls 401 and501 rotate to roll optical plastic layer 270 onto glass substrate layerto bond optical plastic layer 270 to glass substrate layer 250 with anoptically clear adhesive layer 460. Layer 460 may include attributesdescribed in connection with intermediate layer 260.

FIG. 5 illustrates an example lamination technique of coupling opticalplastic layer 270 to glass substrate layer 250, in accordance withaspects of the disclosure. Lamination is one example of fabricating ahybrid plastic-glass blank of the disclosure. In FIG. 5 , rolls 501 and502 rotate to press optical plastic layer 270 onto glass substrate layerto bond optical plastic layer 270 to glass substrate layer 250 with anoptically clear adhesive layer 460.

FIGS. 6 and 7 illustrate a diamond turning technique of forming aprescription surface 777 in optical plastic layer 270 of a hybridglass-plastic lens blank, in accordance with an embodiment of thedisclosure. Diamond turning, polishing, grinding, etching, or othersubtractive process may be deployed to form a prescription surface 777of FIG. 7 . Alternatively, coupling optical plastic layer 270 to glasssubstrate layer 250 may include casting, injection-molding, orover-molding the optical plastic layer 270 to glass substrate layer 250.In that context, prescription surface 777 may be formed by the mold andcuring the optical plastic layer 270 may include curing optical plasticlayer 270 with heat or ultraviolet (UV) radiation to form a prescriptionoptical element 711. Prescription optical element 711 may be used aslens 120 in FIG. 1 , for example.

FIG. 6 illustrates chuck 687 securing hybrid plastic-glass lens blank310 for diamond-turning a prescription surface 777 into the opticalplastic layer 270 with a diamond bit 280 in a subtractive process. FIG.7 illustrates a plastic center thickness dimension 779 of opticalplastic layer 270 at a central optical axis 695 of the prescriptionsurface 777. Prescription surface 777 is formed opposite planar surface775 of optical plastic layer 270. In an embodiment, plastic centerthickness dimension 779 is less than 200 microns. Dimension 779 may beless than 100 microns, in some embodiments. In an embodiment, dimension779 is 50 microns or less. Glass substrate layer 250 may have athickness 759 of 400 microns or less. A total center thickness ofprescription lens 711 (e.g. dimension 779 plus dimension 759) may beless than 500 microns. In a conventional plastic lens, a centerthickness that is 500 microns or less would not provide suitablerigidity for the prescription lens. However, the hybrid plastic-glassprescription lens 711 has the rigidity characteristic of glass substratelayer 250. This allows prescription lens 711 to be much thinner andlighter than conventional lenses.

FIG. 8 illustrates an example hybrid glass-plastic prescription opticalelement 899, in accordance with an embodiment of the disclosure. FIG. 8illustrates example optical layers that may be added to a prescriptionoptical element after a prescription surface 777 is formed. Prescriptionsurface 777 is illustrated as planar in FIG. 8 to assist with thedescription of the additional optical layers, although those skilled inthe art appreciate that prescription surface 777 may include aspherical, aspherical, or freeform curvatures. Additionally, the opticallayers presented in FIG. 8 are not necessarily drawn to scale.

In FIG. 8 , a hard-coat layer 837 is disposed on prescription surface777. Hard-coat layer 837 may be configured to prevent scratches formingonto prescription surface 777. An anti-reflective (AR) layer 835 may beformed over hard-coat layer 837. The AR layer 835 may be a multi-layerAR layer. An anti-static coating 833 may be formed over AR layer 835 andan anti-fog layer 831 may be disposed over anti-static coating 833.

Similarly, hard-coat layer 847 is disposed on planar surface 253 ofglass substrate layer 250. Anti-reflective (AR) layer 845 may be formedunder hard-coat layer 847. And, an anti-static coating 843 may be formedunder AR layer 845 and an anti-fog layer 841 may be disposed onanti-static coating 843. Other optical layers may optionally be added tooptical element 899.

Layers 841, 843, 845, and 847 may be considered plastic layers. Inaddition to providing anti-scratch, anti-reflective, anti-static, and/oranti-fog attributes, one potential advantage of adding any of layers841, 843, 845, and 847 may be that a second plastic layer (in additionto plastic layer 270/770) is added beneath glass substrate layer 250.Consequently, glass substrate layer 250 is confined between two plasticlayers.

FIG. 9 illustrates a flow chart for a process of fabricating aprescription optical element, in accordance with aspects of thedisclosure. The order in which some or all of the process blocks appearin process 900 should not be deemed limiting. Rather, one of ordinaryskill in the art having the benefit of the present disclosure willunderstand that some of the process blocks may be executed in a varietyof orders not illustrated, or even in parallel.

In process block 905, a glass substrate layer (e.g. layer 250) isprovided. The glass substrate layer may have a thickness of 400 micronsor less.

In process block 910, an optical plastic layer (e.g. optical plasticlayer 270 or 770) is coupled to the glass layer.

Coupling the optical plastic layer to the glass substrate layer mayinclude laminating the optical plastic layer to the glass substratelayer. An intermediate layer may adhere the glass substrate layer to theoptical plastic layer.

Coupling the optical plastic layer to the glass substrate layer mayinclude roll-to-roll bonding of the optical plastic layer to the glasssubstrate layer.

Coupling the optical plastic layer to the glass substrate layer mayinclude casting, injection-molding, or over-molding to the opticalplastic layer to the glass substrate layer.

Coupling the optical plastic layer to the glass substrate layer mayinclude curing the optical plastic layer with heat or ultravioletradiation.

In process block 915, a prescription surface is formed into the opticalplastic layer. A plastic center thickness of the optical plastic layermay be 200 microns or less after the prescription surface is formed.

Forming the prescription surface may include a subtractive process thatincludes at least one of grinding, diamond turning, or polishing theoptical plastic layer to form the prescription surface of the opticalplastic layer.

Process 900 may further include forming a bevel or groove into theprescription optical element to aid in securing the prescription opticalelement into frames. For example, the prescription optical element maybe secured to frame 102 of FIG. 1 .

Embodiments of the invention may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,and any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a head-mounted display (HMD) connectedto a host computer system, a standalone HMD, a mobile device orcomputing system, or any other hardware platform capable of providingartificial reality content to one or more viewers.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (“ASIC”) orotherwise.

A tangible non-transitory machine-readable storage medium includes anymechanism that provides (i.e., stores) information in a form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

The above description of illustrated embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes, variousmodifications are possible within the scope of the invention, as thoseskilled in the relevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. A method of fabricating a prescription optical element, the method comprising: providing a glass substrate layer; coupling an optical plastic layer to the glass substrate layer; and forming a prescription surface on an eyeward side of the optical plastic layer that is opposite an object side of the optical plastic layer, wherein the object side is a planar surface that overlays the glass substrate layer, and wherein the glass substrate layer has a glass thickness to provide rigidity to the prescription optical element.
 2. The method of claim 1, wherein coupling the optical plastic layer to the glass substrate layer includes laminating the optical plastic layer to the glass substrate layer, wherein an intermediate layer adheres the glass substrate layer to the optical plastic layer.
 3. The method of claim 1, wherein coupling the optical plastic layer to the glass substrate layer includes roll-to-roll bonding of the optical plastic layer to the glass substrate layer.
 4. The method of claim 1, wherein coupling the optical plastic layer to the glass substrate layer includes casting, injection-molding, or over-molding the optical plastic layer to the glass substrate layer.
 5. The method of claim 4, wherein coupling the optical plastic layer to the glass substrate layer includes curing optical plastic layer with heat or ultraviolet radiation.
 6. The method of claim 1, wherein forming the prescription surface includes a subtractive process that includes at least one of grinding, diamond turning, or polishing the optical plastic layer to form the prescription surface of the optical plastic layer.
 7. The method of claim 1 further comprising: forming a bevel or groove into the prescription optical element to aid in securing the prescription optical element into frames.
 8. The method of claim 1, wherein the glass thickness is 400 microns or less.
 9. The method of claim 1, wherein a plastic center thickness of the optical plastic layer is 200 microns or less after the prescription surface is formed. 